螺旋桨模型喷气降噪试验与实船效果预报研究

螺旋桨若发生空化,空化就是全船最主要的辐射噪声源。采用喷气降噪技术可以降低螺旋桨的空化噪声。试验证实,在螺旋桨推力损失不大时,采用导边喷气、喷气环喷气、组合喷气三种方式都可以使噪声谱级大幅下降。根据喷气孔出口速度的无量纲值相等可以换算出实船喷气量。实船预报表明,采用喷气后总声级降低5 d B以上。

Model propeller noise reduction by air injection and full-scale propeller noise prediction

Once the cavitation caused by propeller occurs, it will be the strongest noise source. Noise can be reduced by using air injection system. Model experiment results show that injecting air from propeller leading edge, from air ring or from both leading edge and air ring can all reduce the noise, and the effects are all very remarkable. Also, the injected air quantity for full-scale propeller can be calculated according to the demand that the dimensionless air speed at the holes'' outlet must be equal. The full-scale propeller noise prediction shows that the total sound pressure level can decrease by more than 5 dB.